diff --git a/src/LayerResolver/Resolvers/NamespaceLayerResolver.php b/src/LayerResolver/Resolvers/NamespaceLayerResolver.php
index 4ec15878..5b8d3506 100644
--- a/src/LayerResolver/Resolvers/NamespaceLayerResolver.php
+++ b/src/LayerResolver/Resolvers/NamespaceLayerResolver.php
@@ -9,6 +9,7 @@
 
 use function str_starts_with;
 use function strlen;
+use function usort;
 
 /**
  * Resolves a layer by matching the file path against registered layer paths.
@@ -22,12 +23,21 @@
     /**
      * Layer paths stored with a trailing '/' so a single str_starts_with()
      * against the file path (also suffixed with '/') covers both exact and
-     * descendant matches.
+     * descendant matches. Kept in declaration order for resolveAll().
      *
      * @var array<string, list<string>>
      */
     private array $normalisedLayers;
 
+    /**
+     * The same paths flattened and sorted longest first, so resolve() can
+     * return on the first match: it is always the most specific layer.
+     * Equal lengths keep declaration order.
+     *
+     * @var list<array{0: string, 1: string}> [layerPath, layerName]
+     */
+    private array $layerPathsLongestFirst;
+
     /**
      * @param array<string, string|list<string>> $layers  Map of layer name → path prefixes
      */
@@ -35,40 +45,35 @@ public function __construct(
         array $layers,
         string $basePath,
     ) {
-        $normalisedLayers = [];
+        $normalisedLayers       = [];
+        $layerPathsLongestFirst = [];
 
         foreach ($layers as $layerName => $layerPaths) {
             foreach ((array) $layerPaths as $layerPath) {
-                $normalisedLayers[$layerName][] = Path::normalise(
-                    Path::resolve($layerPath, $basePath),
-                    canonicalise: true
-                ) . '/';
+                $normalisedPath = Path::normalise(Path::resolve($layerPath, $basePath), canonicalise: true) . '/';
+
+                $normalisedLayers[$layerName][] = $normalisedPath;
+                $layerPathsLongestFirst[]       = [$normalisedPath, $layerName];
             }
         }
 
-        $this->normalisedLayers = $normalisedLayers;
+        usort($layerPathsLongestFirst, static fn (array $a, array $b): int => strlen($b[0]) <=> strlen($a[0]));
+
+        $this->normalisedLayers       = $normalisedLayers;
+        $this->layerPathsLongestFirst = $layerPathsLongestFirst;
     }
 
     public function resolve(string $className, string $filePath): ?string
     {
         $pathWithSlash = Path::normalise($filePath, canonicalise: true) . '/';
-        $matchedLayer  = null;
-        $matchedLength = -1;
 
-        foreach ($this->normalisedLayers as $layerName => $layerPaths) {
-            foreach ($layerPaths as $layerPath) {
-                if (str_starts_with($pathWithSlash, $layerPath)) {
-                    $length = strlen($layerPath);
-
-                    if ($length > $matchedLength) {
-                        $matchedLayer  = $layerName;
-                        $matchedLength = $length;
-                    }
-                }
+        foreach ($this->layerPathsLongestFirst as [$layerPath, $layerName]) {
+            if (str_starts_with($pathWithSlash, $layerPath)) {
+                return $layerName;
             }
         }
 
-        return $matchedLayer;
+        return null;
     }
 
     /**